Today's society, at least in the industrialized parts of the world, has become almost totally dependent upon electricity. This presents several problems. First, the demand upon generation and transmission capacity occasionally overcomes the ability to generate and distribute enough power to meet the demand. This leads to all too common power brownouts and, in extreme cases, to complete blackouts. A second problem involves building transmission and distribution lines reaching into more and more remote regions as the population abandons urban and suburban areas and moves to such remote areas. Also, although stand-alone electrical generator systems have long been available for use in areas not served by the electrical transmission grid, the use of such portable generators presents another set of problems.
Portable generators, powered by a hydrocarbon fuel such as gasoline or diesel fuel typically produce inordinate amounts of pollution relative to the amount of electrical power generated. As the world struggles with greenhouse gas effects, such pollution becomes more and more problematic. Also, fuel must transported to the portable generator's location which may also present logistical, cost, and safety problems. For example, in dry woods or forest regions, even a small spark, such as from an improperly spark-suppressed internal combustion engine used by a camper or other visitor could start a forests fire.
Solar energy is emerging as a source of electrical power for use in remote areas. While solar power is generally non-polluting, the capital expense is typically high. In addition, many parts of the world experience insufficient sunshine to make solar power totally reliable at a particular time of need. Even in more sunny climes, of course, solar power cannot be generated at night.
Fuel cells are yet another portable source of electrical power. At the present time, at least two problems prevent their widespread use, at least in non-military applications. Initial cost of small, portable fuel cells is still high. In addition, many fuel cells require gaseous hydrogen as a fuel which is not yet readily available in the consumer market. Hydrogen also presents a safety hazard if improperly handled.
Human and animal-powered electrical generators have also been used but, heretofore, have not provided practical amounts of electricity to operate a refrigerator, for example, for extended periods of time.